Method and device for automated application of lacquered films to body parts, and automation-compatible lacquered composite

ABSTRACT

A method and an apparatus for automated application of paint film to bodywork parts ( 1 ) and to a paint film composite ( 5 ) which is suitable for automation. A paint film composite ( 5 ) which is suitable for automation is created and adhesively bonded onto the bodywork part ( 1 ) in an accurate position and without any bubbles or creases by means of a robot-controlled application tool that is appropriate for this purpose. To securely hold the film composite ( 5 ), which has been picked up from a substrate, the suction grippers ( 30, 31 ) which grip the ends are angled in mirror-image form, in order in this way to prevent the ends from becoming detached from the suction grippers. The lower protective strip ( 9 ) is then at least partially pulled off, thus exposing the adhesive face of the useful part ( 6 ) of the paint film. The film composite ( 5 ) is aligned in the correct orientation at a short distance from the bodywork part ( 1 ) and the useful part ( 6 ) of the paint film is wiped onto the bodywork surface ( 1 ).

The application claims the priority of German Patent Document No. 102 30034.8, filed 4 Jul. 2002 and PCT/EP2003/005154, filed 16 May 2003 thedisclosure of which is expressly incorporated by reference herein,respectively.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a method and an apparatus for automatedapplication of paint film to bodywork parts and to a paint filmcomposite which is suitable for automation. In this case, the inventionis based on a method for automated application of self-adhesive film tobodywork parts. German reference DE 196 42 831 A1 and DE 198 09 515 A1are examples of prior art methods of such application to body parts.With regard to the paint film composite, reference should be made as theknown generic type to DE 195 32 998 A1.

In the case of vehicles, the bodywork surface which is located betweentwo adjacent glass surfaces is frequently intended, for stylisticreasons, to have a high-gloss paint film, which is colored blackirrespective of the color of the rest of the vehicle, bonded over it, inorder to give the impression of a continuous glass surface at thispoint. To be precise, this relates in particular to the two adjacentvertical frame struts of the window frames in the area of the centerpillar of the vehicle. At least one of these frame struts is arranged onthe window frame of a side door. Since these bodywork surfaces aregenerally only in the form of narrow strips, the blank of the paint filmto be applied also has a correspondingly elongated form and is notparticularly large, so that the corresponding paint film blank can behandled manually by just one person without any problems. Since, on theother hand, the paint film remains on the vehicle throughout its entireuseful life, the paint film must be appropriately and permanentlyadhesively bonded to the bodywork. In this case, it should be rememberedthat the side struts to be adhesively bonded over in this way arelocated in the direct field of view of the vehicle users, at least onentering the vehicle, and the requirements for perfect film applicationare thus particularly stringent.

German reference DE 195 32 998 A1 discloses a flat blank for aself-adhesive paint film, which is intended to be applied without anybubbles or creases to the frame strut of a window frame. In order toavoid trapped air enclosures (bubbles) between the bodywork and thepaint film, the latter is provided, at least in areas which are at risk,over the entire surface area with a large number of microscopic ventingopenings which are arranged in the form of a grid. Any air enclosurescan escape without any problems through these venting openings. Becausethe venting openings are so small they do not interfere—at leastinitially—with the external appearance of the bodywork part to which thepaint film has been applied. The venting openings arranged in the formof a grid are also intended to increase the spatial adaptationcapability of the paint film, and to reduce the risk of creases beingformed. This document admittedly says nothing about the way in which thefilm is applied—manually or in an automated form, but the overallimpression of this document leads to the supposition that the paint filmcan be applied only manually. Furthermore, this document does notdisclose the complete structure of the film composite, which includesthe paint film blank ready for processing, in the delivery state. Ingeneral, it should be noted as a critical factor of this prior art thatthe large number of microscopic venting openings will in fact becomevisible over the course of time owing to weather influences and agingprocesses, so that the paint film will become unattractive.

It can be assumed that the paint film blank which is provided with ahighly intensively adhesive adhesion bonding layer on its lower facerepresents a film composite having a total of three layers in thedelivery state in which it is ready for processing, in which aprotective film or a protective paper is in each case adhesively bondedboth over the lower face and on the high-gloss visible face of the paintfilm blank. In this case, the protective paper on the lower face isprovided on the contact face with the adhesive bonding layer of thepaint film blank with an antistick coating, so that it can be detachedfrom the intensively adhesive bonding layer of the paint film relativelyeasily, and in particular without tearing into the paint film. Theprotective paper on the upper face is provided on the contact face withthe outside of the paint film blank with an only slightly adhesivebonding layer, so that this protective paper can also easily be detachedfrom the paint film.

When paint films are being applied manually, the protective film stripson the lower face or adhesive face are removed completely, so that theadhesive face of the paint film is exposed. The protective film stripwhich still adheres to the visible face of the paint film is set backwith respect to the end of the paint film according to the descriptionin the abovementioned German reference DE 195 32 998 A1, so that theremaining film composite has to be handled on the paint film blankitself. For application, the paint film—guided manually at both of itsends—is aligned by eye in the stretched state a short distance above thebodywork part to be bonded over, and one end of the paint film ispressed against the bodywork, in the correct position. One importantfactor in this case is that the boundary edges of the paint film blankare not covered by any outer protective paper in the end area. Whilemanually maintaining the tensile stress in the paint film which has beenfirmly adhesively bonded at one end, it is pressed against the bodyworkfrom the end which has been firmly adhesively bonded towards the otherend along a progressing pressure line using the hand which has becomefree. This contact pressure is repeated with an increased linear forceby means of a flexible wiper, preferably in the form of a hard piece offelt, in order to improve the adhesion. Once the outer protective striphas been pulled off, those edges of the paint film which project beyondthe frame strut at the side are then bent around the edges of thebodywork part, and are likewise pressed on the rear face.

Manual application of paint films to the vehicle bodywork has variousdisadvantages. On the one hand, the paint films can be positioned withonly little accuracy, leading to frequent reworking. In this case, itshould be remembered that there is no exact reference mark on thebodywork for alignment of the film blank by eye. If the alignment is notcorrect, the paint film may either be seated at a slight angle, so thatthe edges, whose dimensions are short, run poorly, or the film blank isseated too high or too low. When applied to the two window frame strutswhich are immediately adjacent to one another in the area of the centerpillar, a different height position of the paint films may in somecircumstances be highly disturbing. A further disadvantage is that, evenif the paint film runs smoothly on the bodywork and a large contactpressure is applied to the paint film to press it onto the frame strut,air enclosures frequently occur between the two items, although theseare frequently not evident until after a certain delay. The air which isadsorbed on the adhesive layer is initially included in the form ofmicroscopic and inconspicuous small bubbles. This primary air slowlymigrates within the adhesive layer and gathers to form larger smallbubbles, which produce local bulges in the paint film. These smallbubbles which appear only retrospectively must be rectified byreworking, that is to say by deliberately puncturing them with needles.It has also been found that the complete removal of the lower protectivefilm strip, that is to say the exposure of the adhesive face of thepaint film, leads to dust particles accumulating on this adhesive layerwhich, in some circumstances, may be evident in an unpleasant manner onthe visible face of the applied paint film. The process of pulling offthe protective film strip creates a certain electrostatic potential,which attracts dust particles and bonds them to the adhesive layer.Particles deposited between the paint film and the bodywork can berectified only by tediously removing the applied paint film during areworking step and, in some circumstances, applying a new paint filmafter the bodywork has been cleaned. The reworking (which has manycauses) in the case of manual application of paint film has an adverseeffect on productivity, and considerably increases the production costs.In addition to all that has been stated, it should be noted that manualapplication of paint film is monotonous but nevertheless requires a highdegree of care, and that powerfully manually pressing the paint film inplace is not only very tiring but, if such stress is long-lasting, canalso lead to adverse health effects, for example to inflammation oftendons and their sheaths, or to joint pains.

As a result of all these difficulties, efforts are also already beingmade to change to providing the stylistic function of the paint film,specifically on the central frame struts of the side windows, to givethe impression of a continuous glass surface by means of a hard plasticpart covered with a high gloss black-colored paint, which is clippedand/or screwed to the frame strut at the appropriate point. Apart fromthe fact that a hard plastic part such as this, including the fittingmeans, is considerably more expensive than a paint film blank, this alsorestricts the internal area by the physical height of the hard plasticpart, for predetermined external vehicle dimensions. Apart from this, ahard plastic part such as this and the fitting means are also heavierthan a paint film blank.

German reference DE 196 42 831 A1 discloses an apparatus and a methodfor application during series production of self-adhesive protectivefilm to vehicle bodyworks. The protective film is used as transportpackaging for brand-new vehicles while the vehicle is being transportedfrom the factory to the vehicle dealer. The protective film is pulledoff the bodywork again before the vehicle is handed over to thecustomer. Since the protective film is used only temporarily, itsadhesion capability is only relatively low. It should be possible topull it off the bodywork again easily after use, in particular withouttearing into it or leaving behind any residues on the bodywork. The filmneed adhere only sufficiently firmly to ensure that it cannot becomedetached from the bodywork on its own as a result of the wind of motionand/or weather influences during transportation. The bodywork parts tobe protected include, in particular, the large-area horizontal surfaces,that is to say the roof, the engine hood and the trunk lid. The driver'sdoor is also bonded over, for protection reasons.

According to German reference DE 196 42 831 A1, the protective film isprovided as a virtually endless material web on a supply roll forapplication, with the adhesive face of the outer layer within the filmcoil lying directly on the outer face of the film layer adjacent to iton the inside, that is to say being bonded to it—corresponding to thelow adhesion capability of the protective film. A reasonable,rectangular piece is pulled off the supply roll and is cut to length forapplication of the protective film, with two opposite longitudinal sidesof the film blank each being held firmly by a robot-controlled holdingstrip in the form of a respective suction strip, holding the film blankin the stretched-out state. If required, specific parts, for example forfittings, can be cut out of the film blank in this stretched-out state.The film blank is then aligned above the bodywork part over which it isto be bonded, by means of the handling robot, and is applied to theappropriate bodywork part with the film blank being moved towards thevehicle surface. Since the bodywork parts to be bonded over are slightlycurved, a relatively small contact zone, located approximatelycentrally, results first of all as the film blank is moved closer to thebodywork component and its size becomes larger as the film blank ismoved closer until, finally, the entire horizontal surface is bondedover virtually without any bubbles or creases. The already appliedprotective film is then pushed on along a progressive pressure line, bymeans of a weighted felt wiper which corresponds to the shape.

The known application technique for the only slightly adhesive,large-area protective films, which are provided in the form of wound-up,virtually endless, single-layer material webs, cannot be transferred tothe application of small-area paint film blanks which are provided in anindividually prefabricated form, in each case as a three-layer filmcomposite. Apart from this, the requirements for position accuracy,freedom from bubbles and creases in the applied paint film areconsiderably more stringent than in the case of protective films.

An object of the invention is to improve the method which forms thegeneric type and the corresponding apparatus such that paint film blankscan be applied to sought-out bodywork areas in an automated form, suchthat reworking can very largely be avoided, despite the qualityrequirements being much more stringent than those for protective films.Furthermore, the invention is intended to provide a paint film compositewhich is suitable for automation and by means of which the applicationof the paint film can be carried out in an automated manner.

According to the present invention, a paint film composite, which issuitable for automation, is first of all created and is adhesivelybonded onto the bodywork part in an accurate position, and without anybubbles or creases, by means of a robot-controlled application tool thatis suitable for this purpose. In order to securely hold the filmcomposite which has been picked up from a table or the like, the twosuction grippers which grip the ends are angled in mirror-image form, inorder in this way to prevent the ends from becoming detached from thesuction grippers. The lower protective strip, which is gripped by amoving gripping tool on a pulling-off lug which projects at the end, isat least partially pulled off, thus exposing the adhesive face of theuseful part of the paint film. The film composite, which is heldstretched out, is aligned in the correct orientation at a short distanceaway from the bodywork part which is to be bonded to and is heldinflexibly, and the useful part of the paint film is wiped onto thebodywork surface by a moving wiper, from its separated position. Theouter protective strip, which is still held firmly by the suctiongripper, is then pulled off the applied paint film. Expedientrefinements of the invention can be found in the respective dependentclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in the following text with reference tovarious exemplary embodiments, which are illustrated in the attacheddrawings, in which:

FIGS. 1 and 2 show a longitudinal section (FIG. 1) and a plan view (FIG.2) through and respectively of a film composite which is suitable forautomation and has a paint film blank to be applied, with the directlyinvolved components of the application tool as shown in FIG. 3 and ofthe bodywork likewise also being illustrated,

FIG. 3 shows a side view of a robot-controlled application tool whenmoving towards a stacking apparatus, which is likewise illustrated andin which a specific supply of film composites to be applied is held inthe correct position, with the pivoting bearing for the suction grippersof the application tool being arranged concentrically with respect toeach of the mutually facing edges,

FIG. 4 shows the same side view as that in FIG. 3 of a modifiedapplication tool, with the pivoting bearing being formed by recessedjournal bearings, but with a constant stress on the picked-up filmcomposite being ensured by the angling of the suction grippers by virtueof a movable bearing for the end suction gripper,

FIG. 5 shows a vertical section through the application tool shown inFIG. 4 parallel to the view shown in this figure, showing the device forpulling off the outer protective strip,

FIGS. 6 to 8 show three different phases during the application of apaint film blank to a bodywork part, specifically the start of thewiping-on process in FIG. 6, the end of the wiping-on process in FIG. 7,and with the outer protective strip being pulled off the applied paintfilm in FIG. 8,

FIG. 9 shows a side view of a further variant of an application tool, inwhich the start-side suction gripper is mounted on a recessed pivotingjournal and the end suction gripper is mounted by means of a four-barlinkage such that it can pivot such that the facing boundary edge of theend suction gripper is moved during the pivoting of the suctiongrippers, on the basis of the magnitude and direction, in the samedirection as the corresponding boundary edge of the start-side suctiongripper,

FIG. 10 shows an enlarged individual illustration of the long-nosepliers, which can be driven to rotate, for the already illustratedapplication tools with a lower jaw part which can be pivoted through 90°in order to grip and handle the pulling-off lug on the film compositeand in order to wind up the protective strip,

FIGS. 11 and 12 show a greatly enlarged section illustration (FIG. 11)and a view (FIG. 12) on a smaller scale of another embodiment oflong-nose pliers, which have a jaw lower part which can be movedparallel, and can be moved backward and forward as an entity by thewidth of the film composite,

FIG. 13 shows a partial view of a further exemplary embodiment of anapplication tool, illustrating the protective film pulling-offapparatus, with the gripping tool which is driven such that it canrotate in this case being in the form of a suction strip which has aD-shaped cross section and at the same time acts as a coil core,

FIGS. 14 a and 14 b show a cross section (FIG. 14 a) and a view of theopen suction face (FIG. 14 b) of the suction strip of the protectivefilm pulling-off apparatus shown in FIG. 13,

FIGS. 15 a and 15 b show a cross section (FIG. 15 a) and a view of theopen suction face (FIG. 15 b) of a modified refinement of the suctionstrip, as could be used in the protective film pulling-off apparatusshown in FIG. 13,

FIGS. 16 a, b, c show three different exemplary embodiments of filmcomposites with an intermediate supporting film in the end projections,and

FIGS. 17 a, b show two different exemplary embodiments of filmcomposites without a supporting film in the end projections.

DETAILED DESCRIPTION OF THE DRAWINGS

The method according to the invention for automated application ofself-adhesive paint film to bodywork parts is dependent on the paintfilm to be applied being prefabricated in the form of blanks 6, whichare produced in a suitable form for robots. The bodywork part to becovered with paint film may, for example, be a vertical limb, which islocated in the area of the center pillar of a vehicle, of a window framein a side door, whose outer surface requires the film blank to have anelongated shape. A bodywork part 1 such as this is indicated bydashed-dotted lines in FIGS. 1 and 2 and by solid lines in FIGS. 6, 7and 8. In order to apply it, a film blank is gripped on the non-adhesiveouter face at two opposite ends by means of suction grippers to which avacuum can be applied, is held stretched out, is aligned accurately inposition above the bodywork part to be bonded onto in this state, and isadhesively bonded to it.

In order to allow the prefabricated paint film blanks 6 to betransported and to be handled in an automated manner, they must each beprovided on the outside and underneath with an adherent but easilydetachable protective strip 8, 9, that is to say must be included in afilm composite, with the drawings showing different embodiments of thefilm composites 5 (FIGS. 1, 2, 6 and 16 a), 15 (FIG. 16 b), 15′ (FIG. 16c), 16 (FIG. 17 a), 16′ (FIG. 17 b). These variants will be described inmore detail further below, although the description will first of all becontinued on the basis of the exemplary embodiment shown in FIGS. 1, 2and 16 a. It is important for correct handling and application of thepaint film blank that each of the two protective strips 8, 9 projectbeyond the useful length L of the blank at the two ends, which arelocated in the area of the narrow faces of the blank, where they formprojections 10 and 11, respectively, on which the film composite can beheld firmly by means of suction grippers 30 and 31, respectively, towhich a vacuum can be applied, without having to cover the area of thepaint film blank 6 itself.

The length, measured in the longitudinal direction of the blank 6, ofthe end projection 11 is approximately matched to the attachment widthb₂ of the associated end suction gripper 31 measured in the longitudinaldirection of the paint film blank 6. The length of the other, start-sideprojection 10 is admittedly likewise approximately matched to theattachment width b₁ of the associated start-side suction gripper 30.However, the start-side projection 10 is lengthened, at least withrespect to the lower protective strip 9, by a specific gripping length lbeyond the application width b₁ which has been mentioned, so that apulling-off lug 12 is also formed by this gripping length l.

The film composite 5 which is designed in this way and contains thepaint film blank 6 is offered to be picked up by the application tool ina defined orientation with the outer protective strip 8 freelyaccessible in the working area of a freely programmable industrialrobot, which is provided with an application tool 20. This offering ofthe film composite in a defined orientation for transfer by the handlingrobot can be carried out in various ways as well as in differentorientations. The important factor in this case is that, firstly, theposition, which is defined precisely by mechanical stops or the like, ofthe film composite to be transferred does not change during the transferprocess, that is to say it must be offered on a fixed substrate. On theother hand, the film composite must not rest on a rigid substrate. Thiscould lead to permanent pressure points on the paint film to be appliedin the event of minor orientation discrepancies, which can never beavoided completely, between the substrate and the picking-up plane 21 ofthe suction grippers 30, 31 in the application tool 20. This point willbe discussed in more detail further below in conjunction with FIG. 3. Atthis point, it should just be noted that the film composites 5 arepreferably offered to the application tool for transfer stacked in ahorizontal position. In order to allow the film composites to be stackedas far as into the projections, and to lie flat in the stack, asupporting film 7, which corresponds to the thickness of the paint film6, is in each case inserted between the two protective strips 8, 9 inthe area of the projections 10 and 11, so that the film composite 5 isformed with three layers over its entire length—apart from certaininterruptions—and has a uniform thickness D. The thickness of theindividual layers of the film composite is illustrated in an exaggeratedform in order to illustrate this more clearly in FIG. 1.

Two suction grippers 30, 31 are provided on the working face 22 of theapplication tool 20, and their sucking picking-up surfaces 32 arelocated on a standard picking-up plane 21. Their positions and sizescorrespond to the projections 10 and 11 which have been mentioned on thefilm composite 5. In a corresponding manner to the start-side and endprojections, the suction grippers will be referred to as the “start-sidesuction gripper” 30 and the “end suction gripper” 31. The two suctiongrippers can be fitted with their sucking picking-up surfaces to theupper protective strip 8 in the area of the two projections 10, 11, withthe vacuum then being applied, so that the film composite to be pickedup is transferred from the offered position to the application tool.

While the film composite 5 is being handled during the applicationprocess, there is a risk of the film composite being raised by thesucking picking-up surfaces 32 of the suction grippers—starting from theboundary edge 33 or 33′ which in each case faces the paint filmblank—with air incorrectly being blown into the interior of the suctiongrippers so that air is at least partially introduced into the suctiongripper or grippers. This would very greatly reduce the fixing force ofthe suction grippers, or would even cancel it out completely. In orderto prevent this, the two suction grippers 30, 31 are each pivotedthrough a specific angle α, α′, respectively, from the picking-up plane21 after the transfer of the film composite 5. The projections 10, 11 onthe film composite 5 which has been picked up and is held stretched outthen project obliquely and approximately in mirror-image form withrespect to one another from the picking-up plane 21 in the direction ofthe rear face 23 of the application tool, as is indicated bydashed-dotted lines in the figures. However, suitable design precautionsmust be taken with the suction grippers 30 and 31 and with theirpivoting bearing to ensure that the tensile stress in the film compositeis changed no more than negligibly by the pivoting movement. This willbe discussed in more detail further below in conjunction with thedescription of the individual alternatives of the application tool 20,20′ and 20″. At this point, it will just be mentioned that the magnitudeof the pivoting angle α, α′ of the suction grippers 30, 31 is greaterthan the largest angle β which occurs during the application processbetween the film composite 5 on the one hand and the connecting linebetween the two boundary edges 33, 33′, which are located on thepicking-up plane 21, of the opposite suction grippers on the other hand(see FIG. 6). With regard to the absolute magnitude of the pivotingangles α, α′ of the suction grippers, a pivoting angle in the range from10 to 60°, preferably 15 to 45° can be recommended in this context.

As preparation for the application of the paint film, the lowerprotective strip 9 is pulled off the paint film blank, initially usingthe pulling-off lug 12 on the start-side projection 10 for this purpose.This pulling-off lug is gripped by a gripping tool 50, which can movewithin the application tool, and the lower protective strip 9 is thuspulled off the film composite, starting at the start-side projection 10in the exemplary embodiment illustrated in FIGS. 1, 2, 6 and 16 a, withthe entire adhesive face of the paint film blank 6 progressively beingexposed.

In conjunction with the process of pulling the lower protective strip 9off the film composite, it is on the one hand possible to pull thisprotective strip 9 completely off the film composite before theapplication process and only then to start the process of application ofthe paint film, for which there are once again different options, whichare described further below in conjunction with the description relatingto FIGS. 16 b, 16 c and 17 a, 17 b. Bearing in mind the risk of anelectrostatic potential being produced in the remaining film compositeas a result of the lower protective strip being pulled off, which canattract particles from the surrounding area to the exposed adhesive faceof the paint film 6, where they can become firmly attached, it isadvisable to keep the time interval between pulling the protective strip9 off and adhesive bonding of the paint film 6 to the bodywork part 1 asshort as possible, and to change the position of the remaining filmcomposite as little as possible during this period. This aim is bestachieved by not pulling off the lower protective strip until during theapplication process, that is to say simultaneously with the application.If the paint film 6 is adhesively bonded onto the bodywork part 1immediately after the protective strip 9 has been pulled off, then thepaint film application process can be carried out in the normal factoryenvironment—instead of in the clean room conditions which wouldotherwise possibly be required.

Once the lower protective strip has been at least partially pulled offthe film composite 5, which is held stretched out in the applicationtool 20, the film composite 5 is aligned in the correct orientation withthe paint film blank 6 at a short distance from the bodywork part 1which is to be bonded to and is held firmly in the defined orientationand inflexibly. The paint film blank 6 is then wiped onto the bodyworkpart 1 to be bonded to from the stretched-out separated position bymeans of a flexible wiper 90, 91 which can move longitudinally withinthe application tool 20. Finally, the upper protective strip 8 is pulledoff the outer face of the completely applied paint film blank 6 by meansof a pulling-off movement of the application tool 20, in particular ofthe end suction gripper 31. For this purpose, the application tool 20 ispivoted away from the bodywork surface 1 about a virtual pivoting axiswhich is located in the vicinity of the start-side suction gripper 30,as is indicated by the arrow shown by solid lines in FIG. 8. Instead ofor in addition to this, the application tool 20 can be moved in thedirection of the start-side end of the paint film blank 6. One and/orthe other of these movements of the application tool results in the endsuction gripper 31 pulling the outer protective strip 8 off the paintfilm blank 6, which has been completely applied to the bodywork part 1.

In order to pull the lower protective strip 9 off simultaneously withthe application process in an advantageous manner, during theapplication process, the lower protective strip 9 is first of all onlypartially pulled off the film composite, and the adhesive face of thepaint film blank 6 is only partially exposed. The rest of the process ofpulling the protective strip 9 off and the exposure of the adhesive faceof the paint film blank 6 then take place corresponding to the progressof the process of wiping the paint film blank 6 onto the bodywork part.In this case, the paint film blank 6 is wiped onto the bodywork part 1in only a single direction and with only one wiper 90, 91.

During this process of pulling the lower protective strip 9 offsimultaneously with the application process, an approximately constantdistance A (see FIG. 5 or 6) is maintained between the progressingpulling-off point 69 on the protective strip that is to be pulled off,on the one hand, and the wiper 90, 91, which is following it and islikewise progressing, on the other hand. In order to make it possible tocarry this out using a simple and physically compact application tool,the process of pulling off the lower protective strip 9 is carried outby the superimposition of a translational linear movement of a windingdevice on the one hand and the rotational winding movement of thewinding device on the other hand. The winding device, which winds up theprotective strip 9 that has been pulled off, is moved furthertranslationally during the winding process at a speed which matches thespeed of the wiper. Furthermore, the protective strip 9 is pulled off bymeans of the winding process—in its own right—at a speed whichcorresponds to the circumferential speed of the coil, which must be setsuch that it matches the speed of the wiper 90, 91. The translationspeed and the winding speed are in this case superimposed.

In order to prevent unacceptably great expansion in the film composite5, and in particular in the paint film blank 6, particularly towards theend of the wiping-on process, the end suction gripper 31 is movedtowards the bodywork surface 1 to be bonded over (see FIG. 7). At thesame time, the end projection 11 of the film composite 5, which isgripped by the end suction gripper 31, can in this phase be allowed tocontinue sliding, which can be achieved by deliberately reducing thevacuum in the end suction gripper 31, in the sense of reducing theholding force.

It is important for good adhesion of the applied paint film to thebodywork for the paint film blank 6 to be wiped on with a very highlinear pressure during the application process. To be precise, thislinear pressure should be in the range from 10 to 50 N/cm, andpreferably 20 to 30 N/cm.

It is not so simple on the one hand to make it possible to exert suchhigh linear pressures while, on the other hand, nevertheless making itpossible to produce a linear pressure which is as uniformly high aspossible over the entire wiper width despite slight curvature orinclination of the bodywork surface to be bonded over. Furthermore, nopressure points should remain on the paint film to be applied despitethe high linear pressures. In order to take account of all this, thepaint film blank 6 is wiped on using a wiper 91 composed of a hard feltwith a thickness of about 10 to 20 mm.

Starting with the paint film composite which is aligned accurately in aposition above the point at which it is to be applied to the bodyworkpart and held at a short distance from it (see, for example, FIG. 6),the wiper 91 is placed on the film composite and is guided along thefilm composite with a high contact pressure within the application tool,with the application tool being locked in a fixed position above thebodywork part in the longitudinal direction of the paint film blank. Inthis case, the adhesive face of the paint film 6 is wiped onto thebodywork surface with a high linear pressure, with very small gasenclosures being forced out of the adhesive join, as it progresses,during this process. In addition, air which has become adhesively bondedto the exposed adhesive layer is first of all forced out by the highwiper linear pressure. In consequence, not only does the paint filmadhere very firmly to the bodywork surface, but it is also impossiblefor microscopic gas enclosures to accumulate retrospectively to formvisible gas bubbles because, as stated, there are no longer any gasenclosures remaining in the adhesive joint.

One special feature of the paint film application to vertical framelimbs of passenger vehicle side doors is that, once the paint film blankhas been correctly adhesively bonded onto the flat face of the framelimb, its projecting side edges must be bent around and must be pressedonto the rear face. If no robot tool has yet been provided for thispurpose, this can be done in the conventional manner manually, in somecircumstances with the assistance of special handtools for pressing itonto the rear face.

Following the fundamental explanation of the method for automatic paintfilm application, various features and/or variants of a film compositewhich is suitable for automation will first of all also be dealt with,with reference to FIGS. 16 a, b, c and FIGS. 17 a, b, to the extent thatthis has not already been done in conjunction with the description ofthe application method, before describing, further below, details of thedesign of the application tool 20, 20′, 20″. Various exemplaryembodiments of film composites, which will first of all be dealt with inthe following text with reference to their corresponding features, areillustrated in the drawings.

The outer protective strip 8 is provided with a reasonably stronglyadhesive layer, so that it can be pulled off the paint film 6 without alarge amount of force and, in particular, without leaving any residue.The lower protective strip 9, on the other hand, is provided with anantistick coating, so that it can likewise be pulled off the verystrongly adhesive layer of the paint film 6, without being torn into orbeing delaminated. It is desirable for the lower protective strip 9 tobe automatically detached from the adhesive face of the paint film blank6 when it is bent through a sharp angle, that is to say when it is bentwith a small bending radius. In any case, the lower protective strip 9should be more easily detachable from the adhesive face of the paintfilm or of the supporting film than the outer protective strip 8 fromthe outer face of the paint film.

The film composite 5 according to the exemplary embodiment shown inFIGS. 1, 2, 6 and 16 a has been used as the basis for the description ofthe application method dealt with above. This film composite 5 has thecommon feature with the other exemplary embodiments shown in FIGS. 16 b,16 c, 17 a and 17 b that both the start-side and end projections 10 and11 (FIGS. 16 a, 16 b and 16 c) and the projections 10′ and 11′ (FIGS. 17a and 17 b) are provided, on which the film composite can be held firmlyoutside the paint film blank 6. A supporting film 7 whose sizecorresponds to the thickness of the paint film is inserted between theouter and the lower protective strips 8 and 9, respectively, in the areaof the projections 10 and 11, so that the film composites 5, 15 and 15′have the same thickness D in the area of these projections 10 and 11 asin the area of the paint film blank 6. The film composites 5, 15 and 15′are accordingly particularly highly suitable for being offered in astacked form. In contrast, in the case of the film composites 16 and 16′shown in FIGS. 17 a and 17 b, there is no supporting film in the area ofthe projections 10′ and 11″, which reduces the cost. These filmcomposites can admittedly not be stacked particularly flat or in aplanar form when in relatively large quantities, but they may still bein a sufficiently flat and planar form when the quantities in the stackare small. This type of film composite may in fact be usable when themanufacturing batch sizes per shift are small.

In the case of all three film composites 5, 15 and 15′ (exemplaryembodiment as shown in FIGS. 16 a, 16 b, 16 c), the supporting film 7may be identical to the paint film 6. In any case, the supporting filmshould be detached from the usable part of the paint film blank 6 bymeans of an interruption 13, such that it is detached from the paintfilm 6 without any further measures.

In conjunction with the FIGS. 1, 2, 6 and 16 a, it should also bementioned that, in the case of this exemplary embodiment, a supportingfilm 7 of the same thickness as the paint film 6 is inserted between theouter protective strip 8 and the lower protective strip 9 not only inthe two projections 10 and 11, but also in each case in the pulling-offlug 12 which in this case is provided only at the start-side end. Apartfrom small interruptions 13 and 14, the film composite 5 has threelayers over its entire length, that is to say even into the pulling-offlug 12. This results in a thickness D which is uniform over the entirelength of the film composite 5, so that these film composites can bestacked flat and in a planar form even in relatively large quantities.

In order to ensure the pulling-off function of the pulling-off lug 12for the film composite 5, only the lower protective strip 9 is formedcontinuously into the pulling-off lug 12 while, in contrast, the outerprotective strip 8 and the supporting film 7 are provided with a narrowslot 14 along a transverse line locally over the entire width of thefilm composite 5. This slot runs transversely with respect to thelongitudinal direction of the film composite 5 along a line which islocated in the area between the start-side projection 10 and thepulling-off lug 12.

The exemplary embodiment of the film composite 15 shown in FIG. 16 bdiffers from that shown in FIG. 16 a only in the design of thepulling-off lug 12′, which has a single layer in the case of the filmcomposite 15 and is an integral component of the lower protective strip9. Since the film composite need be laid flat and in a planar form onlyin the area of the paint film blank and of the projections 10 and 11during the stacking process, the pulling-off lug 12′ can hang downsomewhat without any problems within the stack of film composites. Assoon as one film composite has been picked up in the application tool,the associated pulling-off lug 12′ projects into the area of thegripping tool (which is indicated by dashed-dotted lines in FIG. 16 b)of a pulling-off apparatus which is integrated in the application tool;the pulling-off lug 12′ can be gripped securely by this gripping tooldespite hanging down to a certain extent.

In the case of the film composite 15′ illustrated in FIG. 16 c, not onlyis a (single-layer) pulling-off lug 12′ provided on the (three-layer)start-side projection 10, but a pulling-off lug 12″ is also arranged atthe outermost end of the end projection 11; both pulling-off lugs arepart of the lower protective strip 9. This type of embodiment of thefilm composite 15′ is intended for complete removal of the lowerprotective strip 9 from the film composite before application of thepaint film blank. This process of pulling the lower protective strip offcompletely can be carried out within the application tool by the twopulling-off lugs 12′ and 12″ of the film composite 15′ which has beenpicked up in the application tool being gripped by moving gripping toolswhich are integrated in the application tool and being moved away fromthe firmly held film composite transversely with respect to thepicking-up plane, as is indicated by dashed-dotted lines in FIG. 16 c.As soon as the lower protective strip 9 has been completely detachedfrom the film composite, the protective strip which has been pulled offcan be thrown away into a scrap container by opening the gripping tools.The advantage of the film composite 15′ and of the previous completeremoval of the lower protective strip 9 before the application of thepaint film is that the application tool can be designed to beconsiderably simpler than one in which the lower protective strip isremoved during the application process. In some circumstances, itappears that this method of operation may be acceptable in clean roomconditions, which nowadays are widely used for automobile paintingsystems.

The further exemplary embodiment of a film composite 16 which isillustrated in FIG. 17 a largely corresponds, apart from the projections10′ and 11′, which have two layers, that is to say they have noprotective film between them, to the film composite which is shown inFIG. 16 b. The film composite 16 has three layers only in the area ofthe paint film blank 6 itself. The pulling-off lug 12′ which is fittedat the start end has only a single layer. This film composite 16 isparticularly cost-effective, owing to the absence of the interposedsupporting films, but cannot be stacked flat and in a planar form inrelatively large numbers into the area of the projections 10′ and 11′.If the numbers of film composites 16 within a stack are small, reliableand accurately positioned transfer of a film composite to theapplication tool may, however, nevertheless be possible. Since a(single-layer) pulling-off lug 12′ is provided only at the start-sideend in the case of the film composite 16, this film composite issuitable for the lower protective strip to be removed at the same timeas the application process, as has already been described further abovein conjunction with FIGS. 1 to 3 and 5 to 8.

The last exemplary embodiment, which is illustrated in FIG. 17 b, of afilm composite 16′ differs from that illustrated in FIG. 17 a in that—ina similar way to that in the case of the film composite shown in FIG. 16c—a (single-layer) pulling-off lug 12″ is also provided at the rear endof the film composite 16′. This film composite 16′ is thus suitable forcomplete removal of the lower protective strip 9 from the film compositewithin the application tool before the application of the paint filmblank.

With regard to the apparatus used as a machine for automated applicationof self-adhesive paint films to bodywork parts, the application toolwhich has already been mentioned a number of times should be mentionedhere in particular, as is illustrated in various exemplary embodiments20, 20′ and 20″ in the drawings. Irrespective of the embodiment, therear face 23 of the application tool is fitted to the hand joint 25 ofthe working arm 24 of a freely programmable industrial robot and can behandled by it freely in three dimensions. Two suction grippers 30 and31, to which air or a vacuum can be deliberately applied are arranged ata distance from one another on the opposite flat face of the applicationtool, specifically on the working face 22, and can be used to grip theprefabricated paint film blank 6, which is contained in a film compositethat is suitable for automation, at two opposite ends on the outside, tohold it stretched out, and not only to be freely handled in this stateby the industrial robot or application tool, but also to be applied inan accurate position to the bodywork part 1.

The areas of correspondence between the various application tools 20(FIGS. 1-3 and 5-8), 20′ (FIG. 4) and 20″ (FIG. 9) will be describedfirst of all. In all three exemplary embodiments, the two suctiongrippers 30 and 31, 30′ and 31′ and, respectively, 30″ and 31″ are ineach case mounted in the application tool such that they can pivot, andare provided with a pivoting drive 37, 40, 40′. The sucking picking-upsurface 32 of the suction grippers can thus be pivoted onto a standardpicking-up plane 21—the picking-up position—for transferring a paintfilm composite 5 (which is provided in a flat planar form) on the onehand, or to a working position, on the other hand, with these twopositions being approximately in mirror-image form with respect to oneanother. In the pivoted working position, the sucking picking-upsurfaces 32 project obliquely from the picking-up plane 21, that is tosay at an angle α, α′ in the direction of the rear face 23 of theapplication tool. This pivoting movement of the suction grippers is usedto ensure that the gripped projections 10 and 11 of the film compositeare held firmly on the suction grippers despite the stretched-out filmcomposite being pushed in a V shape from the picking-up plane during theapplication process—see, by way of example, the angle β in FIG. 6. Thecapability of the suction grippers to pivot is physically designed suchthat the tensile stress in the film composite that has been picked up ischanged no more than negligibly by a pivoting movement of the suctiongrippers 30, 31. This means that the mutually facing boundary edges 33and 33′ of the sucking picking-up surfaces 32 must not be any furtherapart from one another after the pivoting movement of the suctiongrippers than before the pivoting movement. The various exemplaryembodiments of the application tools differ from one another in terms ofthe design solution to this problem, although this will not be describeduntil further on in the following text.

In conjunction with the corresponding features of the variousapplication tools 20, 20′ and 20″, the pivoting levers 36, 36′, on whichthe pivoting drives 37 (FIGS. 3 and 9) as well as 40 and 40′ (FIG. 4)act, and, furthermore, the associated preferably adjustable stops whichdefine the picking-up position and the working position of the suctiongrippers, should also be mentioned. In the case of the application tool20 shown in FIG. 3, the stops 38 and 38′, respectively, define thepicking-up position, which is illustrated by solid lines, while thestops 39 and 39′, respectively, define the respective working positionsof the suction grippers 30 and 31, which are indicated by dashed-dottedlines. The stops which define the picking-up position of the suctiongrippers 30′ and 31′ are annotated 43 and 43′ for the application tools20′ shown in FIG. 4 while, in contrast, the stops which are responsiblefor the working position are provided with the reference symbols 44 and44′. Finally, the corresponding reference symbols for the applicationtools 20″ with the suction grippers 30″ and 31″ as shown in FIG. 9should also be mentioned: stops 47 and 47′ for the picking-up position(solid lines), and stops 48 and 48′ for the working position(dashed-dotted lines).

In the case of all of the described application tools, a gripping tool50, 50′, 80, 80′, which can be moved parallel and various embodiments ofwhich are illustrated, is furthermore arranged in a corresponding manneradjacent to the start suction gripper 30, 30′, 30″, which grips thestart-side projection 10 of the film composite. This gripping tool ismounted such that it can move and is provided with an appropriatemovement drive such that it can on the one hand be moved onto thepicking-up plane 21 alongside the start suction gripper such that it isready to pick up—the start position. On the other hand, the grippingtool can be moved from this start position under the picking-up plane 21onto a working plane 53 for the gripping tool, and within this workingplane parallel to said working position and parallel to itself. Thefurther details of the gripping tool itself will be described furtherbelow in conjunction with the individual exemplary embodiments relatingto this. At this point, it should just be noted that the gripping toolsin all of the illustrated exemplary embodiments are mounted such thatthey can rotate, are coupled to an appropriate rotary drive and are usedas a coil core for the lower protective strip 9, whose end is gripped.For this purpose, the gripping tool is mounted such that it can rotatein an angled drive 54 which is arranged laterally offset alongside thesuction grippers 30 and 31 and from which it projects freely in theaxial direction. The gripping tool can be caused to rotate deliberatelyby means of the drive motor 55 for winding-up purposes.

The physical design of the moving guidance of the gripping tool isillustrated in a corresponding form in the various exemplary embodimentsof application tools; this can best be seen in FIG. 5. In the exemplaryembodiment shown there, the gripping tool is in the form of long-nosepliers which are mounted such that they can rotate and by means of whichthe protective strip 9, whose end is gripped, can also be wound up atthe same time.

The drive block of the gripping tool, which comprises the angled drive54 and the motor 55, is coupled by means of parallelogram guides 56 to acarriage 59, so that the drive block and the long-nose pliers can bemoved translationally on a circular arc from the start position, whichis illustrated by solid lines in FIG. 5, to the working position, whichis indicated by dashed-dotted lines. In the start position—which isdefined by the stop 58 attached to the carriage 59—the center of thelong-nose pliers is at the same level as the picking-up plane 21 of theapplication tool. In contrast, after they have been moved to theirworking position on the working plane 53, the long-nose pliers arelocated underneath the picking-up plane. The working position is definedby the stop 58′, which is likewise attached to the carriage 59. A linearmovement drive 57 in the form of a working cylinder is provided in orderto move the drive block and the long-nose pliers from the start positionto the working position, and vice versa, which working cylinder in theillustrated exemplary embodiment connects two diagonally opposite hingepoints of the four-bar linkage, which is covered by the twoparallelogram guides 56 and their joints. The carriage 59 is guided onguide rods 60 such that it moves parallel to the picking-up plane 21.The carriage and the long-nose pliers can be moved parallel to theworking plane 21 by means of a linear movement drive 61, which isattached to the application tool and is in the form of a workingcylinder whose piston rod is coupled to the carriage 59. The linearmovement of the carriage 59 corresponds at least to the length L of thepaint film blank 6 to be applied.

Bearing in mind this not inconsiderable length L of the required linearmovement of the carriage 59, the physical length of the applicationtool, which is located horizontally in the figures, is particularlylarge, specifically because not only the linear movement which has beenmentioned or the guide rods 60 but—at least in the illustrated exemplaryembodiments—the length of a working cylinder of corresponding length asthe linear movement drive 61 for the carriage 59 must also beaccommodated on the application tool, as well. If the paint film blanksto be applied are very long, for example blanks which must be appliedover the width of the roof of the bodywork, it may thus in somecircumstances be expedient for the linear movement drive for thecarriage to be in the form of a spindle drive, in which case the spindlecan be arranged in a space-saving form between the guide rods.

With regard to the position and orientation of the gripping tool and ofthe long-nose pliers with respect to the physical depth relative to theplane of the drawing in the various illustrations of the applicationtools, it should be noted that the long-nose pliers are located in thesame area as that in which the suction grippers 30, 31, which havealready been mentioned, and the film composite which has been picked upby them are also located. The wiper 90, which is described furtherbelow, is likewise fitted to the carriage 59 and is used to wipe thepaint film onto the bodywork, is also located in the same area. Thedrive block 54/55 for rotation of the gripping tool must therefore lieon a plane beyond the gripping tool, the suction grippers, the filmcomposite and the wiper.

In principle, it would also be feasible to move the moving gripping toolonly linearly within the working plane in order to grip the end of thelower protective strip and to pull it off the film composite—apart fromchanging the gripping tool from the start position to the working plane53—so that there is no need for a complex rotary drive for the grippingtool. However, at least when there is a requirement for the protectivestrip to be pulled off at the same time as the application process, thiswould be dependent on the linear movement of the gripping tool guided inthis way corresponding to twice the length L of the paint film blank tobe applied; furthermore, the gripping tool guided in this way would haveto be driven at twice the speed of the carriage 59 which guides thewiper 90/91. This is all dependent not only on complex duplicatedcarriage guidance but also on very considerable physical lengths of theapplication tool, making the latter unnecessarily heavy and cumbersome.The gripping tool, which is mounted such that it can move, istherefore—as stated—at the same time in the form of a winding apparatusin the illustrated exemplary embodiments, so that it can be heldtogether with the wiper 90, 91 on the carriage 59 and can be movedtogether with it, although this equally allows the lower protectivestrip to be pulled off the paint film at the same time as theapplication process.

The already mentioned wiper 90, 91, which is arranged within theapplication tool and is used in the actual application phase should bementioned as a further physical component of the application tools 20,20′, 20″ which is significant to the method. This is arranged such thatit can move in two ways, and is provided with an appropriate linearmovement drive. On the one hand, the working edge of the wiper can bemoved from a waiting position, which is illustrated by solid lines inFIG. 5 and in which it is pushed back from the picking-up plane 21, to aworking position which is indicated by dashed-dotted lines and islocated close to the picking-up plane 21, and in the working position itcan be pressed with a specific force against the bodywork part 1 towhich the paint film is to be applied. For this purpose, thecarriage-like wiper holder 90—as can be seen most clearly in FIG. 5—ismounted on a carriage guide 93, which is inclined with respect to thepicking-up plane 21, and is provided with an appropriate adjustmentdrive 92 in the form of a working cylinder, which also applies thecontact force to the wiper. On the other hand, the wiper can be moved ina straight line and parallel to the picking-up plane 21 when in theworking position. In order to allow this, the carriage guide 93 in theexemplary embodiment illustrated in FIG. 5 is itself arranged on thealready mentioned carriage 59, which is also indirectly fitted with thedrive block 54/55, which is held such that it can pivot, for thelong-nose pliers. The linear movement drive 61 can be used to move thecarriage and the wiper 91 parallel to the working plane 21, with thepaint film 6 being wiped onto the bodywork part 1 with a specific linearpressure.

As has already been mentioned, the paint film must be wiped on with avery high linear pressure during the actual application phase although,on the other hand, the bodywork surface is slightly curved. In order tomake it possible to produce a linear pressure which is as uniformly highas possible over the entire wiper width at the same time, andnevertheless not cause any pressure points on the paint film to beapplied, the wiper 91 is composed of a hard felt.

As can be seen from FIG. 3, a horizontal stacking platform 96, which ismounted elastically on a base frame 100 and has side holding and guidewebs 97, 98, is arranged in the working area of the industrial robotsuch that it handles the application tools 20, and on which horizontalstacking platform 96 the film composites can be stacked to form a stack95 and can thus be offered lying horizontally to the application tool20. The holding and guide webs 97, 98 at the sides are used to align thefilm composites contained in the stack accurately in position one abovethe other. For the sake of completeness, it should be mentioned that thestacking platform need not be aligned exactly horizontally, althoughthis arrangement is recommended by preference. In specific cases, aslight inclination of the stack may possibly be worthwhile.

In the illustrated exemplary embodiment, the stacking platform, which iselastically supported underneath, is guided by means of side guidejournals in vertical elongated holes in the guide webs 98, so that thestacking platform can not only be moved vertically but can also betilted to a limited extent about the longitudinal axis defined by theguide journals 99, while maintaining its defined position with respectto the horizontal coordinates. This tilting capability is made possibleby the elastic intermediate elements 104 between the supporting pillars101 and the lower face of the stacking platform. A certain amount ofaxial compression allowed by the elastic intermediate elements alsoallows limited free tilting of the stacking platform about a pivotingaxis at right angles to the plane of the drawing. Furthermore, the guidepillars 101 can move in vertical guides 102 and are clamped by means oflinear movement springs 103 in an upper limit position, which is boundedby stops (adjusting nuts 105). This also allows the stacking platform toflex translationally in the vertical direction. This flexibility of thestacking platform, which is elastic in a number of ways even if limited,is important for the careful picking up of the film composite, which isoffered on the stacking platform, by the robot-controlled applicationtool. Any position or orientation discrepancies which are within therange of the movement tolerance of the industrial robot between the filmcomposite offered for transfer on the one hand and the transfer positionof the application tool on the other hand cannot cause any damage to orpressure points on the film composite by virtue of this flexibility,because the stacking platform can automatically and freely match itselfto any minor position or orientation discrepancy of the applicationtool.

With the stacking platform being vertically flexible, it wouldintrinsically be feasible for the application tool to be moved towardsthe film stack 95 from above in the vertical direction and for thesuction grippers 30 and 31 to be placed on the upper end of the stack,in which case this placement can be detected by tactile sensors ofwidely differing types and in widely different arrangements. However,this would mean that the application tool would have to move through agreater or lesser distance in an inching mode before reaching the stack95, depending on the remaining height of the stack, in order to preventthe suction grippers from striking the stack too hard, and this woulddisadvantageously lengthen the cycle time.

In order to avoid this, the stacking platform 96 is held at a variableheight and is provided with a controllable height adjustment drive suchthat the upper edge of the stack 95 is always at a constant heightlevel, irrespective of the number of film composites stacked on it.

In the case of the exemplary embodiment illustrated in FIG. 3, thecontrolled height adjustment of the stacking platform is achieved by thefollowing physical components. The upper edge of the stack is recordedby an adjustable height light barrier 109, which has two light beams, atslightly offset heights, with separate detectors. When the heightadjustment is in the rest state, the lower light beam should be darkenedby the stack while, in contrast, the upper light beam must not bedarkened. If the lower light beam is not darkened, then the stack isslowly raised until the lower light beam is darkened by the stack onceagain. If, in contrast, both light barriers are darkened, then the stackis slowly lowered, to be precise until, and only until, the stack nolonger obstructs the upper light beam.

The signal from the light barrier is passed indirectly via a suitablecontroller 110 to an electrical adjusting motor 107, which raises orlowers the stacking platform as required. For this purpose, thesupporting pillars, which are guided in the vertical guides 102 suchthat they cannot twist, are provided with adjusting spindles 106underneath. Adjusting nuts 105 which act as movement-limiting stops canbe screwed thereto, abut underneath against the end face of the verticalguides 102, and determine the height of the supporting pillars 101. Thesupporting pillars are continuously prestressed upwards by the linearmovement springs 103, and hold the adjusting nuts against the stop. Theadjusting nuts themselves can be rotated by the adjusting motor 107 viaa toothed belt 108, raising or lowering the stacking platform dependingon the rotation direction of the adjusting nuts.

A stacking platform such as this, or a similar stacking platform whichis elastically flexible in a limited manner is also provided for theother application tools.

The method of operation of the exemplary embodiments of the applicationtool shown in FIGS. 1 to 9 will now be described in the following text,with a distinction being drawn between a preparation phase for theapplication process, and the actual application phase:

In the preparation phase for the application process, once the filmcomposite 5 has been picked up in the application tool 20, the long-nosepliers 50 grip the pulling-off lug 12, which is fitted to the start end,of the film composite that has been picked up. The two suction grippersthen pivot from the picking-up position, which is illustrated by solidlines in FIG. 4, to the angled working position, which is illustrated bydashed-dotted lines in FIG. 5, with the lower protective strip and thesupporting film being detached from the outer protective strip in thearea of the start-side projection, at the start-side end of the filmcomposite, by virtue of the relative movement of the start-sideprojection 30 with respect to the long-nose pliers 50, which areinitially still fixed in the waiting position. The long-nose pliers arenow moved from the start position to the working position or to theworking plane 53, with the winding drive 55 being switched on at thesame time. In this phase, the winding speed is matched to the linearmovement speed of the long-nose pliers on the initial circular arc insuch a way that that part of the lower protective strip 9 which has beenpulled off the film composite is on the one hand wound with a specificdensity onto the long-nose pliers while, on the other hand, a specificinitial section of the adhesive face of the paint film blank is exposed.The position of the drive block 54/55 at the end of this preparationphase for the application process is indicated by dashed-dotted lines(left-hand position) in FIG. 5. At least the last processes in thispreparation phase preferably take place with the application toolalready being in a position in which the film composite is aligned inthe correct position at a short distance in front of the bodywork part.The actual application phase of the paint film blank starts from theposition of the drive block 54/55 which is shown by dashed-dotted linesand is indicated on the left in FIG. 5.

At the start of the actual application phase, the wiper 90/91 is loweredfrom the waiting position, which is illustrated by solid lines, in thedirection of the arrow onto the film composite 5, which is stretched outon the picking-up plane, with an edge, which is composed of felt, of thewiper blade 91 that is held in the wiper holder 90 at the bottom beingplaced down in front of the paint film blank 6 in the area of the filminterruption 13, as shown of FIG. 6. Once the paint film is wiped ontothe frame limb of the window frame with the vehicle side door, which issupported in a fixed position and in a defined orientation, being in theinstalled state, the illustration in FIGS. 6 to 8 is accordingly chosento be in the vertical position. The contact pressure exerted on thewiper causes the film composite to be pressed against the surface towhich it is to be applied of the bodywork part 1 that is locatedalongside, with the film composite first of all being pressed out of thestretched-out position in a V-shape. The shorter limb of the filmcomposite which has been stretched to a V-shape in this case initiallyassumes a maximum angle of β with respect to the picking-up plane 21,which angle β must be less than the pivoting angle α of the startsuction gripper 30 in order that the film composite cannot be detachedfrom the sucking contact surface of this suction gripper. Starting withthe wiper 91 in the initial position shown in FIG. 6, it is now movedalong the film composite within the application tool with a high contactpressure, with the application tool being locked in a fixed positionabove the bodywork part in the longitudinal direction of the paint filmblank.

While the paint film is being wiped onto the bodywork surface, thelong-nose pliers 50, which are driven in a winding sense, are movedforwards translationally at the same speed as the wiper and at aconstant distance A from the wiper. At the same time, the long-nosepliers are driven at an angular velocity such that the lower protectivestrip 9, which is detached from the paint film at the detachment point69 as it moves forwards, is wound up continuously and tightly to form acoil 68. In this case, the circumferential speed of the winding processis constant, and is specifically equal to the translational speed of thewiper while, in contrast, the rotation speed of the long-nose pliers 50decreases as the coil diameter increases. The form composite 5 issupported by the coil as it becomes larger, in the area of thedetachment point 69 as it moves forwards.

FIG. 7 illustrates the end of the wiping process. The wiper 91 hasreached the end of the paint film blank 6, and the coil 68, which is nowalready very large, of the lower protective strip is already locatedoutside the bodywork part. The end suction gripper 31 has been movedtowards the bodywork part towards the end of the wiping process in orderto ensure that the spreading angle β′ of the form composite with respectto the picking-up plane 21 does not become too large, but in any casedoes not become any larger than the pivoting angle α′ of the end suctiongripper 31, in order to ensure that the end projection 11 remains heldfirmly on the suction gripper. The vacuum in the interior of the endsuction gripper 31 is admittedly reduced during this final phase inorder to reduce the holding force, thus allowing the film composite tocontinue sliding without any excessive increase in the tensile stress.It is more important that the holding force, which is defined by themagnitude of the vacuum and is reduced, does not collapse in anuncontrolled manner.

In the stage of the application process shown in FIG. 8, the paint film6 has already been completely adhesively bonded onto the bodywork part1, and the lower protective strip has been pulled completely off thefilm composite and has been wound up to form a coil 68. All that is nowstill necessary is to pull the outer protective strip 8 off the outerface of the applied paint film 6, with this outer protective strip 8still being held firmly at both ends by means of the two suctiongrippers 30 and 31 in the application tool. This pulling-off process iscarried out by means of a large pivoting movement of the applicationtool away from the bodywork part, with the detachment point 69′ of theouter protective strip running from the end of the paint film to itsstart, in the opposite direction to the wiping-on direction. In FIG. 8,the outer protective strip is pulled off by a large movement of the endsuction gripper. However, it would be equally feasible for the outerprotective strip to be pulled off by means of a pulling-out movement ofthe start-side suction gripper.

Once the outer protective strip has been pulled off, both protectivestrips can be thrown away via a scrap container. The outer protectivestrip, which is held by the suction grippers, is thrown away byswitching off the vacuum and by applying air to the suction grippers,which can be done in virtually any desired position of the applicationtool. In contrast, in order to throw away the lower protective stripwhich has been wound up on the long-nose pliers, the application toolmust be moved to a position such that the long-nose pliers are alignedapproximately parallel to the direction of the force of gravity, withtheir free end pointing downwards, so that the loosened coil 68 can fallaway axially from the coil core by the force of gravity whilst thelong-nose pliers have been opened.

As has already been mentioned, one important feature is the capabilityof the suction grippers to pivot while maintaining an approximatelyuniform tensile stress in the film composite that has been picked up,with the various application tools differing from one another in thisrespect.

In the first exemplary embodiment of an application tool 20, which isindicated or illustrated in FIGS. 1 to 3 and 5 to 8, the pivotingjournals 34 of the two suction grippers 30, 31 are arrangedconcentrically with respect to the boundary edge 33, 33′, which facesthe paint film blank 6, of the suction grippers, that is to say thegeometric loci of the pivoting axes are located on the picking-up plane21 of the application tool. The two suction grippers thus pivot aboutthe boundary edges 33 and 33′ in this exemplary embodiment, with theconsequence that the tensile stress in the film composite 5 that hasbeen picked up is not varied by a pivoting movement. The advantage ofthis solution is its physical simplicity; however, it has thedisadvantage that the bearing 35 for the pivoting journals, and even thepivoting journals 34 themselves, project downward beyond the picking-upplane 21 or working face 22 of the application tool, which in somecircumstances may have a disturbing effect on the process of picking upa thin film composite from a flat substrate.

In order to keep the lower face of the application tool underneath thepicking-up plane 21 completely free of components, even though thesuction grippers must be able to pivot with a constant tensile stress inthe film composite which has been picked up, the further exemplaryembodiment of an application tool 20′ as shown in FIGS. 4 and 5 may beused in addition to the application tool 20″ (FIG. 9) which will bedealt with further below, with the features that are of interest herebeing illustrated only in FIG. 4.

The pivoting bearing with the bearing journal 34 and the journal bearing35 for the start-side suction gripper 30′ illustrated on the left are inthe form of a conventional journal bearing, whose center point is offsetwith respect to the picking-up plane 21 of the application tool 20′ inthe direction of its rear face 23 to such an extent that those outlinesof the journal bearing 35′ which are closest to the picking-up plane 21are themselves still offset with respect to the picking-up plane 21 ofthe application tool 20′ in the direction of its rear face 23. Thejournal bearing 35′ of the start-side suction gripper 30′ is likewisemounted immovably on the application tool, in the same way as theassociated separate pivoting drive 40 in the form of a working cylinderwhich acts on the pivoting lever 36.

The situation for the end suction gripper 31′ is different. Admittedly,this suction gripper is also equipped with a conventional journalbearing with a bearing journal 34′ and a journal bearing 35′ which areoffset by preferably the same amount as the start-side suction gripper30′ towards the rear face 23 from the picking-up plane 21. However, thejournal bearing 35′ and the associated, separate pivoting drive 40′ arearranged on a carriage 41 which is mounted such that it can movelongitudinally, so that the end suction gripper 31′ is held on theapplication tool 20′ such that it can move. In order to maintain acertain tensile stress in the film composite that has been picked up,the carriage, and with it the suction gripper, are prestressed, forexample by means of a tensioning spring 42, in the direction of a limitposition which is assumed when picking up a film composite and which, inthe illustrated exemplary embodiment, is predetermined by a stop ring41′ which can be fixed on the carriage guide. Instead of a tensioningspring, a small working cylinder can also be used, by means of which itis possible to apply a variable clamping force which is independent ofthe linear movement, on the film composite.

The method of operation of the maintenance, as illustrated in FIG. 4, ofa specific tensile stress in the film composite which has been picked updespite pivoting of the suction grippers about pivoting journals 34, 34′which are offset with respect to the film plane is now as follows: firstof all, in the picking-up position which is illustrated by solid linesin FIG. 4, the suction gripper picks up a film composite in theapplication tool, with the carriage 41 of the end suction gripper beingin the limit position, which is defined by the stop ring 41′. Thepivoting of the start-side suction gripper 30′ in the clockwisedirection results in the front boundary edge of the contact surface 32being moved to the left through the distance h. The end suction gripper31′ is pivoted through an angle of approximately the same magnitude, butin the opposite pivoting direction, so that the left-hand boundary edgeis moved off its contact surface 32—with respect to the movable systemfor holding the end suction gripper 31′—through approximately the samedistance h to the right, that is to say in the opposite direction to theother suction gripper 30′. This does not in fact lead to an increase inthe tensile stress in the film composite that has been picked up becausethe end suction gripper 31′, which is held such that it can move, canfreely follow the tension which is exerted by the start-side suctiongripper 30′ and is directed to the left in the film composite, butagainst the effect of the tensioning spring 42, in the process travelingover twice the offset distance, specifically the distance 2·h. Theimportant factor in this case is that the start-side suction gripper 30′is held inflexibly in the application tool, and cannot be moved withinthe application tool by any force acting in the tension direction of thefilm composite while it is being wiped on.

The design shown in the exemplary embodiment in FIG. 4 is advantageousfor stabilization of the tensile stress in the film composite that hasbeen picked up during the pivoting movements of the two suction grippersin opposite directions to one another, firstly with regard to thephysically simple journal bearing on the two suction grippers andsecondly with regard to the fact that the picking-up plane 21 of theapplication tool 20′ does not have physical components which projectdownward beyond it and, of course, because the remaining tensile stressin the film composite that has been picked up remains at a controlledlevel. A further advantage is that the application tool 20′ as shown inFIG. 4 can be converted without any problems for different lengths L ofthe film composite or of the paint film to be applied, by virtue of thecarriage 41 for the end suction gripper, specifically just by changingthe position of the stop ring 41′. Taken together, these advantages intheir own right justify the increased complexity for the separatecarriage 41 for the end suction gripper 31′.

9 shows a further exemplary embodiment of an application tool 20″ whichavoids a complex carriage structure. The pivoting bearing 34″, 35″ forthe start-side suction gripper 30″ illustrated on the left in FIG. 9is—in a similar way to that for the application tool shown in FIG.4—likewise in the form of a conventional journal bearing, whose centerpoint is offset by a certain extent in the direction of its rear face 23with respect to the picking-up plane 21 of the application tool 20″, sothat those outlines of the journal bearing 35″ which are closest to thepicking-up plane 21 are still separated in the upper direction from thepicking-up plane 21 of the application tool 20″.

The end suction gripper 31″, which is mounted such that it can pivot,can admittedly likewise move in the longitudinal direction relative tothe application tool 20″, but not by means of a carriage guide. In fact,in the case of the exemplary embodiment shown in FIG. 9, the capabilityof the end suction gripper to pivot is physically combined with itscapability to move longitudinally, which is achieved by means of afour-bar linkage in the illustrated exemplary embodiment. This linkageis formed by two rockers 45 and 45′ which on the one hand are eacharticulated on the end suction gripper 31″, and on the other hand areeach articulated on the application tool 20″. The connecting linesbetween the hinge centers of the rockers 45, 45′ intersect in anydesired movement position of the four-bar linkage, with the mutualintersection of these connecting lines representing the movinginstantaneous center of rotation, that is to say the instantaneouscenter of rotation of the pivoting movement of the end suction gripper31″. 46 denotes the instantaneous center of rotation at the start of thepivoting movement, that is to say the instantaneous center of rotationwhen the suction gripper 31″ is in the picking-up position, while incontrast the instantaneous center of rotation at the end of the pivotingmovement, that is to say when the suction gripper 31″ is in the workingposition, is annotated 46′. The instantaneous center of rotation in theintermediate positions moves on the instantaneous center of rotationpath 46″, which is indicated by dots. The position of the hinge pointsincluding the length of the rockers 45 and 45′ is on the one hand chosensuch that the instantaneous center of rotation 46, 46′ is offsetdownward with respect to the picking-up plane 21 of the application tool20″ in all positions of the suction gripper 31″, that is to say in theopposite direction relative to the picking-up plane to the journalbearing 34″, 35″ for the start-side suction gripper 30″.

Furthermore, the four-bar linkage bearing for the end suction gripper31″ is formed with respect to the mutual arrangement of the hinge pointsand with respect to the length of the rockers 45, 45′ such that theposition offset (distance h′) caused by the pivoting process of thatboundary edge of the end suction gripper 31″ which is close to the blankis of the same size, in terms of magnitude and direction, as thecorresponding position offset distance h′ of the start-side suctiongripper 30″. In this case, the instantaneous center of rotation moves onthe instantaneous center of rotation path 46″ which has been mentioned,and in the process travels through approximately twice the distance(2·h′) in the longitudinal direction of the end suction gripper itself(h′).

The advantage of the pivoting bearing shown in FIG. 9 combines theadvantages of a physically simple configuration with the normaladvantages of the exemplary embodiment shown in FIG. 4. Conversion ofthe application tool 20″ to a different length of the film composite islikewise possible in this case, as long as the frame to which the upperpivoting bearings of the rockers 45 and 45′ and the stops 47′ and 48′are fitted can be screwed on at different positions in the longitudinaldirection of the application tool.

The gripping tool, which has already been mentioned a number of times,is illustrated in various exemplary embodiments owing to its practicalimportance for the application technique. In the case of the exemplaryembodiments which are illustrated in FIGS. 9 and 10 on the one hand andin FIGS. 11 and 12 on the other hand, the gripping tool is in each casein the form of long-nose pliers 50 and 50′, which can rotate and areguided such that they can move, and which each have an upper jaw part(51 and 51′, respectively) and a lower jaw part 52 and 52′,respectively, which each have a constant cross section over their lengthextent. The upper jaw part 51 or 51′, respectively, has a cross sectionin the form of a groove, with the two side edges together covering acontact plane 51″ for the upper jaw part. The lower jaw part movesradially between these side edges while the long-nose pliers are beingclosed.

In the initial position, in which they are ready to pick up, thelong-nose pliers 50 or 50′ must be in such a circumferential positionand the rotary drive must be equipped with an appropriately suitablecontrol means for automatically moving it to this circumferentialposition, in which the upper jaw part 51 or 51′, respectively, isarranged above the picking-up plane 21 while, in contrast, the lower jawpart 52, 52′ is underneath the picking-up plane 21 when it is in theinitial position in which it is ready to pick up.

In the general case, both the upper respective jaw part 51 or 51′ andthe lower jaw part 52, 52′ of the long-nose pliers 50, 50′ can move inthe sense of an opening and closing movement.

Since the application tool approaches the film composite to be picked upfrom above, the upper jaw part 51 or 51′, respectively, may be designedsuch that it does not move in the sense of an opening and closingmovement of the long-nose pliers 50, 50′. In contrast, the lower jawpart 52, 52′ must in this sense be arranged and guided such that it canmove, and must be equipped with an appropriate movement drive. Thedifference between the two long-nose pliers is essentially firstly inthe way in which they are fitted to the pulling-off lug 12 of the filmcomposite to be picked up and how the coil 68 that is produced issubsequently released again, and on the other hand in the nature of theopening and closing movement of the long-nose pliers. In both of theexemplary embodiments of long-nose pliers, it must be possible to pivotto the abovementioned initial position of the long-nose pliersautomatically by a suitable control means in the rotary drive 55 for thelong-nose pliers.

In the exemplary embodiment of the long-nose pliers 50 which isillustrated in FIGS. 9 and 10, the lower jaw part 52 can be pivoted inthe sense of an opening and closing movement of the long-nose pliers 50through 90°, in such a way that, when in the initial position in whichthey are ready to pick up—with the long-nose pliers 50 entirely open—thelower jaw part 52 projects downwards at right angles to the picking-upplane 21 of the application tool 20″. For this purpose, the lower jawpart is connected to the upper jaw part 51 via a pivoting bearing 62,whose pivoting axis is tangentially aligned with respect to thecircumference of the long-nose pliers, and is arranged close to theircircumference. A further pivoting bearing is fitted on the diametricallyopposite side of the lower jaw part 52—offset axially towards the freeend of the long-nose pliers with respect to the pivoting bearing 62—, isat a radial distance from the pivoting bearing 62, and thus forms anoperating lever for the lower jaw part. A toggle lever linkage 63 has anapproximately centrally located toggle link 64 which acts on the lowerend of this operating lever, with the toggle lever linkage beingarticulated at its other end on the upper jaw part 51, at a point whichis offset to the rear with respect to the pivoting bearing 62. Acoupling element 65 acts on the toggle link 64, and can itself beoperated via an operating plunger 66 by a linear movement cylinder 67.This on the one hand allows the lower jaw part 52 to be pivoted to theclosed position, which is illustrated by solid lines, and on the otherhand allows it to be pivoted to the open position, which is indicated bydashed-dotted lines, and in which the lower jaw part projects downwardat right angles from the rotation axis of the long-nose pliers. Theoperating cylinder is provided at its exposed end with a pressure supplyhead, which is not illustrated in FIG. 10 but which allows pressure tobe supplied from a fixed-position circumferential point to the rotatingoperating cylinder.

The advantage of the long-nose pliers 50 shown in FIG. 10 is that notjust they themselves but also their operating drive are designed to bephysically relatively simple and robust. However, this exemplaryembodiment has the disadvantage that the lower jaw part projects wellbelow the picking-up plane 21 while picking up a film composite, that isto say when the long-nose pliers are in the open state. The picking-upplatform must therefore have a cutout at the location of the lower jawpart, which projects when open, or at least must be designed to beappropriately narrow at this point.

long-nose pliers 50′ which are illustrated in an isolated form in FIGS.11 and 12 and which could be installed in the application tool 20 or 20′instead of the long-nose pliers 50 will now be described in more detail.In this case as well, the upper jaw part 51′ is once again arrangedwithin the long-nose pliers such that it cannot move in the sense ofopening and closing. In contrast, the lower jaw part 52′—and onlythis—can be moved toward the upper jaw part, parallel to it, in thesense of closing it, and can be moved back from it in the sense ofopening it. Furthermore, the long-nose pliers as an entity can be movedout of and into the area of the film composite 5 to be picked uptransversely with respect to its longitudinal direction, with themovement distance (transverse linear movement H_(q)) which can becovered by the long-nose pliers corresponding at least to the width ofthe film composite 5 to be picked up, or to the width of the pulling-offlug 12.

In addition to providing the gripping function for the pulling-off lug12 for the film composite—as stated—the long-nose pliers 50′ are alsoused as a coil core for the lower protective strip 9, and canaccordingly be driven to rotate. For this purpose, the long-nose pliersare held on the freely accessible end of a spindle 71, which is itselfmounted in a hollow shaft 70, which is mounted in the angled drive 54′such that it can rotate and can be driven to rotate, such that it cannotrotate but can move axially, by virtue of its external contour not beinground. The axial movement of the long-nose pliers through the transverselinear movement H_(q) takes place only in the open state, and duringclosure only in a rotation position of the long-nose pliers such thatthe upper and the lower jaw parts are respectively positioned above andbelow the film composite to be picked up, or the respective pulling-offlug 12 projecting from it. The long-nose pliers are not closed until theouter end of the transverse linear movement H_(q) is reached, that is tosay when the long-nose pliers have been moved over the entire width ofthe film composite; this situation is illustrated by solid lines in FIG.11, and is indicated by dashed-dotted lines in FIG. 12. The oppositesequence occurs when the long-nose pliers are moved back, that is to sayas soon as the long-nose pliers have been moved axially back from theoutermost end position, they first of all return to the open position,before the return movement then starts to the pulled-back end position,which is illustrated by solid lines in FIG. 12.

An operating cylinder 77 is fitted to the axially opposite end of thespindle for axial movement of the spindle 71 and of the long-nose pliers51′, which operating cylinder 77 revolves with the spindle and mustaccordingly be provided with a pressure supply head 78, which isstationary in the rotation direction, for supplying pressure for the twooperating directions of the rotating operating cylinder, as is indicatedon the extreme right in the figure.

In the exemplary embodiment of the gripping tool illustrated in FIGS. 11and 12, the closing movement and opening movement of the long-nosepliers is coupled to the linear movement drive for them in such a waythat the movement for closing and opening the long-nose pliers isderived from the axial movement of the spindle 70. For this purpose, thelower jaw part 52′ is fitted to a guide rod 72, which is guided suchthat it can move on a circular arc within the hollow spindle 71 by meansof a pair of parallelogram guides 73, with the guide rod not onlycarrying out a radial movement in the sense of opening and closing thelong-nose pliers, but also carrying out a short axial movement h_(a) ofthe guide rod and of the lower jaw part 52′ relative to the upper jawpart 51′, which is rigidly connected to the spindle. The guide rod isstressed in the direction of the open position of the long-nose pliersby means of an opening spring 76 which is fitted to its rearward end. Inorder to use the axial movement of the spindle to derive a means forclosing the long-nose pliers, the front area of the guide rod hasarranged in it a transverse pin 74, which is guided such that it canmove radially in it and projects through axially aligned elongated holesin the spindle as far as the reveal of the non-round internal hole inthe hollow shaft 70. The end face of the hollow shaft is closed at theedge by a stop ring 75 which has axially projecting webs 75′ whichproject into cutouts on the spindle, and in which case the stop ring 75can interact with the transverse pin.

As soon as the transverse pin 74 strikes against the axially projectingweb of the stop ring 75 towards the end of the transverse movement ofthe spindle 71, any further axial movement of the spindle results in theguide rod 72 being fixed, so that it carries out said axial movementh_(a) relative to the spindle against the force of the opening spring76, and in the process moves on the circular arc, which is defined bythe pair of parallelogram guides, relative to the spindle, that is tosay it also moves radially in it in the sense of a closing movement.

The long-nose pliers 50′ shown in FIGS. 11 and 12 have the advantageover the long-nose pliers shown in FIG. 10 that, when they are in thestate in which they are ready to pick up, they can without any problemsbe pulled completely back behind the picking-up plane 21, so that a filmcomposite could be picked up by the associated application tool evenfrom a relatively large, flat table surface.

However, the disadvantage is that the drive is somewhat morecomplicated, because the long-nose pliers have to carry out not only aradial opening and closing movement, but also a relatively largetransverse movement H_(q) in order to fit the opened long-nose pliers atthe side to the pulling-off lug of the film composite which has beenpicked up by the application tool.

gripping tools 80 and 80′, respectively, which are in the form ofsuction strips, as shown in FIGS. 13-15 are considerably simpler,because they are integral and because the gripping function is producedpneumatically by means of a vacuum. FIG. 13 shows an overview drawingrelating to the two exemplary embodiments of suction strips 80 and 80′,respectively, which are shown in detail in FIGS. 14 a, 14 b and 15 a, 15b, respectively. The gripping tool, which can move within the associatedapplication tool, is likewise used as a coil core for the lowerprotective strip 9. It can accordingly be driven to rotate by means ofthe angled drive 54″ and the drive motor 55, and has an approximatelysemicircular or D-shaped cross section. The suction strip, to which airor a vacuum can be applied in a controlled manner, has a sucking contactsurface 88, 88′ on its flat face. The interior of the output drive shaftof the angled drive 54″ to which the suction strip is fitted is drilledsuch that it is hollow axially, with this hole being used as a vacuumsupply. A pressure supply head, which does not rotate at the same time,is fitted to the rearward end of the output drive shaft, which projectsout of the angled drive. The suction strip, which is used as a coilcore, when it is in the state in which it is ready to pick up, must, ofcourse, also be able to be deliberately moved to a rotation positionsuch that the flat picking-up surface of the suction strip, which has aD-shaped cross section, is parallel to the picking-up plane of theapplication tool, or is parallel to the pulling-off lug of the filmcomposite which has been picked up. A vacuum just has to be applied tothe interior of the suction strips, which are fitted to the pulling-offlug, in order to grip the pulling-off lug 12 at the start-sideprojection of the film composite which is to be picked up or has alreadybeen picked up in the application tool.

The suction strips 80 and 80′, respectively, which are illustrated inthe FIGS. 14 a, 14 b and 15 a, 15 b, respectively, differ essentially inthe physical configuration of the sucking picking-up surface 88 or 88′,respectively, which can be fitted to the film composite 5. In the caseof the exemplary embodiment of the suction strip 80 shown in FIGS. 14 a,14 b, a studded metal sheet 81 is swaged in an airtight manner into theopen end of an essentially semicircular tube. The studded metal sheet isprovided with a large number of supporting studs 82 which are arrangedin the form of a grid and are, for example, cylindrical, between whichtransfer openings 83 for the vacuum are fitted. The supporting studsform a very small contact and supporting surface towards the filmcomposite 5 that has been picked up, so that the vacuum that is createdcan act on the film composite, and can hold the film composite firmly,over virtually the entire area of the studded metal sheet that islocated between the side attachment flanges. A vacuum or air can beapplied to the interior of the suction strip via a suction connection 84which passes through the drive shaft of the gripping tool, which is usedas the coil core.

The case of the suction strip 80′ which is shown in FIGS. 15 a, 15 b islikewise based on an essentially semicircular tube, in whose open endhere a grid is formed composed of laminates with, by way of example, alongitudinal web 86 and a large number of short transverse webs 85 whichare incorporated in niches 87. The longitudinal faces of the half-tubewhich are swaged to the transverse webs are ground flush with the gridlaminates in the area of the contact surface 88′. The vacuum can besupplied to the suction strip via a suction connection 84′, which islikewise arranged in the shaft to which the rotating gripping tool isfitted. The advantage of the suction strip 80′ shown in FIGS. 15 a, 15 bover the suction strip 80 is that it has a larger transfer cross sectionfrom the interior of the suction strip to the sucking surface. In thecase of the suction strip 80′ (FIGS. 15 a, 15 b), the transfer crosssection on the one hand and the sucking area on the other hand are ofequal size while, in contrast, there is a major difference in thisrespect between it and the suction strip 80 (FIGS. 14 a, 14 b).

1.-37. (canceled)
 38. A method for automated application ofself-adhesive film to bodywork parts, in which a film blank is grippedon the non-adhesive outer face at two opposite ends by means of suctiongrippers to which a vacuum can be applied, and is held stretched out, inwhich the film blank which is held stretched out is aligned accuratelyin position above the bodywork part to be bonded to and is adhesivelybonded to it, comprising the steps: providing prefabricated, elongatedpaint film blanks in a configuration according to features a to c) forapplication of paint film, and in that the paint film blanks which havebeen provided in this way are moved according to features d) to g) forautomated application: a) including each prefabricated, elongated paintfilm blank in a film composite and provided on the outside andunderneath with an adherent but easily detachable protective strip, witheach of the two protective strips projecting (projections) beyond auseful length (L) of the paint film blank at two ends, which are locatedin the area of the narrow faces of the paint film blank, b)approximately matching the length, measured in the longitudinaldirection of the film blank, of an end projection to an attachment width(b₂) of the associated suction gripper measured in the longitudinaldirection of the paint film blank while, in contrast, the length of astart-side projection is likewise matched approximately to theattachment width (b₁) of the associated suction gripper but with atleast the lower protective strip on the start-side projection beinglengthened by a specific gripping length beyond said attachment width(b₁), c) providing the film composite which includes the paint filmblank is offered in a defined position with the outer protective stripbeing freely accessible in the working area of a freely programmableindustrial robot, which is provided with an application tool, forpicking up by the application tool, d) pushing up the film composite bytwo of said suction grippers, which are provided on the application tooland whose sucking picking-up surfaces are located on a standardpicking-up plane, on the upper protective strip in the area of the endand start-side projections, with the two suction grippers then beingpivoted from the picking-up plane through a respective specific angle(α, α′), in such a way that the projections which have been picked upoff the film composite that is held stretched out, project obliquely andapproximately in mirror-image form with respect to one another from apicking-up plane in the direction of a rear face of the applicationtool, e) pulling off the lower protective strip, starting from astart-side end of the paint film blank and guided by a start-sideprojection, which is used as a pulling-off lug and is gripped by agripping tool, which can move within the application tool thus exposingthe adhesive face of the paint film blank, f) once the film composite,which is held stretched out by the application tool has been aligned inthe correct orientation at a short distance from the bodywork part,which is to be bonded to and is held firmly in the defined orientationand inflexibly, wiping the paint film blank onto the bodywork part to bebonded to, from the stretched-out separated position, by means of aflexible wiper which can move longitudinally within the applicationtool, g) pulling off the upper protective strip from the outer face ofthe applied paint film blank by means of a pulling-off movement of thethe end suction gripper.
 39. The method as claimed in claim 38, whereinthe pivoting movement of the two suction grippers takes place in such amanner that the tensile stress in the picked-up film composite ischanged no more than negligibly by the pivoting movement.
 40. The methodas claimed in claim 38, wherein a magnitude of a pivoting angle (α, α′)of the suction grippers is greater than the largest angle (β) whichoccurs during the application process between the film composite on theone hand and the connecting line between the two boundary edges, whichare located on the picking-up plane), of the opposite suction gripperson the other hand.
 41. The method as claimed in claim 38, wherein asupporting film which corresponds to the thickness of the paint film, isin each case inserted between the two protective strips in the area ofthe projections, so that the film composite is formed with three layersover its entire length—apart from certain interruptions—and has auniform thickness (D) and in that the film composites are provided in astacked form.
 42. The method as claimed in claim 41, wherein the filmcomposites are stacked at least in an approximately horizontal position.43. The method as claimed in claim 38, wherein, at the start of theapplication process, the lower protective strip is pulled off onlypartially and the adhesive face of the paint film blank is initiallyonly partially exposed, and in that the rest of the process of pullingoff the lower protective strip and exposure of the adhesive face of thepaint film blank are carried out corresponding to the progress of theprocess of wiping the paint film blank onto the bodywork part.
 44. Themethod as claimed in claim 38, wherein the paint film blank is wipedonto the bodywork part in only a single direction and with only onewiper.
 45. The method as claimed in claim 38, wherein, during the wipingon process, an approximately constant distance is maintained between theprogressing wiper on the one hand and the likewise progressingpulling-off point on the lower protective strip that is to be pulledoff.
 46. The method as claimed in claim 38, wherein the process ofpulling off the lower protective strip is carried out by thesuperimposition on the one hand of a translational movement of a windingdevice, which winds up the lower protective strip (9) and is moved at aspeed which matches the speed of the wiper, and on the other hand by awinding movement of the winding device, with the winding device likewisewinding up the pulled-off protective strip at a speed which matches thespeed of the wiper.
 47. The method as claimed in claim 38, wherein theend suction gripper approaches the bodywork surface to be bonded overtowards the end of the wiping-on process.
 48. The method as claimed inclaim 38, wherein the end projection of the film composite which isgripped by the end suction gripper is allowed to continue slidingtowards the end of the wiping-on process.
 49. The method as claimed inclaim 38, wherein the wiping-on process is carried out with a linearpressure of between 10 and 50 N/cm.
 50. The method as claimed in claim38, wherein the paint film blank is wiped on by means of a wipercomposed of a hard felt with a thickness of about 10 to 20 mm.
 51. Themethod as claimed in claim 38, wherein, in order to pull the outerprotective strip off the completely applied paint film blank, theapplication tool is pivoted away from the bodywork surface about avirtual pivoting axis which is at least one of located in the vicinityof one of the suction grippers, and is moved in the direction of theopposite end of the paint film blank such that the suction gripper whichhas been moved away pulls the outer protective strip off the appliedpaint film blank.
 52. An apparatus for automated application ofself-adhesive film to bodywork parts, comprising an application toolwhich can be handled by a freely programmable industrial robot and whichhas two suction grippers, which are arranged at a distance from oneanother and to which air or a vacuum can be applied deliberately, on aworking face, which suction grippers can grip one film blank at twoopposite ends on the non-adhesive outer face and can hold it stretchedout, such that the film blank can be handled freely by the industrialrobot in the stretched-out state, in order to carry out the method asclaimed in claim 38, wherein for the application of elongated,prefabricated paint film blanks, which are in each case included in afilm composite which is designed to be suitable for automation and isproduced on an individual basis, the application tool is provided withthe following features: a) the two suction grippers are each arranged inthe application tool such that they can pivot and are provided with apivoting drive such that the suction grippers can be pivoted with theirsucking picking-up surface onto a standard picking-up plane—thepicking-up position—in order to transfer a paint film composite whichhas been provided, or can be pivoted to a working position, whichpositions are approximately in mirror-image form with respect to oneanother, and in which working position the sucking picking-up surfacesproject from the standard picking-up plane in the direction of the flatface of the application tool which is opposite the working face and isreferred to in the following text as the “rear face”, b) a gripping toolwhich can be moved parallel is arranged adjacent to one of the suctiongrippers, which is referred to in the following text as the “startsuction gripper”, and this gripping tool can on the one hand be movedonto the picking-up plane alongside the start suction gripper such thatit is ready to pick up, and on the other hand can be moved from thisstart position under the picking-up plane to a working plane and,furthermore, on the working plane parallel to the working plane andparallel to itself, and c) a wiper is arranged within the applicationtool, can be moved with its working edge from a waiting position, inwhich it has been moved back from the picking-up plane, to a workingposition in which it is located close to the picking-up plane, can bepressed on with a specific force, and in this position can be moved in astraight line and parallel to the picking-up plane.
 53. The apparatus asclaimed in claim 52, wherein a horizontal stacking platform which ismounted elastically, is arranged in the working area of the industrialrobot that is handling the application tool, and has side holding andguide webs, on which the film composites are offered at leastapproximately in a horizontal position to the application tool in astacked form.
 54. The apparatus as claimed in claim 53, wherein thestacking platform is held at a variable height and is provided with acontrollable height adjustment drive, in such a way that the upper edgeof the stack is always at a constant height position, irrespective ofthe number of film composites in the stack.
 55. The apparatus as claimedin claim 52, wherein the pivoting axes of the two suction grippers arelocated on the picking-up plane and close to that boundary edge of thesuction grippers which faces the paint film blank, such that the tensilestress in the picked-up film composite is changed no more thannegligibly by a pivoting movement of the suction grippers.
 56. Theapparatus as claimed in claim 52, wherein: a) the pivoting bearing ofthe start-side suction gripper is in the form of a conventional journalbearing, whose center point is offset with respect to the picking-upplane of the application tool in the direction of its rear face to suchan extent that those outlines of the journal bearing which are closestto the picking-up plane are themselves still offset with respect to thepicking-up plane of the application tool in the direction of its rearface, b) the pivoting bearing for the end suction gripper is in the formof a four-bar linkage with two rockers which are each articulated on theone hand on the end suction gripper and are each articulated on theother hand the application tool, with the moving instantaneous center ofrotation for the pivoting movement of the end suction gripper which iscaused by this being offset in all of its positions with respect to thepicking-up plane of the application tool in the opposite direction tothe journal bearing, c) the four-bar linkage bearing for the end suctiongripper is designed with respect to the mutual arrangement of the hingepoints and the length of the rockers such that the position offset(distance h′), which results from the pivoting, of the boundary edge ofthe end suction gripper close to the blank is of the same size, in termsof its magnitude and direction, as the corresponding position offset(distance h′) of the start-side suction gripper.
 57. The apparatus asclaimed in claim 52, wherein the suction grippers can pivot through afixed pivoting angle (α, α′) which can be predetermined by stops between10 and 45°.
 58. The apparatus as claimed in claim 52, wherein thegripping tool is mounted such that it can rotate and is designed so thatit can be driven to rotate, and has an approximately constant,approximately round cross section over its longitudinal extent, suchthat it can at the same time be used as a coil core for a material whichis in the form of a strip and is gripped by the gripping tool at theend.
 59. The apparatus as claimed in claim 52, wherein the gripping toolis in the form of long-nose pliers which can move within the applicationtool and have an upper jaw part which is arranged above the picking-upplane, at least in the initial position in which it is ready to pickup—and have a lower jaw part, which is arranged underneath thepicking-up plane, wherein only the lower jaw part can move, in the senseof an opening and closing movement of the long-nose pliers.
 60. Theapparatus as claimed in claim 59, wherein the lower jaw part can bepivoted through 90° in the sense of an opening and closing movement ofthe long-nose pliers, such that, in the initial position of thelong-nose pliers, in which they are completely open and are ready topick up, the lower jaw part projects at right angles to the picking-upplane and away from the application tool.
 61. The apparatus as claimedin claim 59, wherein, in the sense of an opening and closing movement ofthe long-nose pliers, the lower jaw part can be moved parallel to itselfin the closing sense towards the upper jaw part, and can be moved awayfrom it in the opening sense, and in that the long-nose pliers as anentity can be moved out of and into the area of the film composite to bepicked up from the side and transversely with respect to itslongitudinal extent, wherein the distance (transverse distance Hq)through which the gripping tool can be moved corresponds at least to thewidth of the film composite to be picked up.
 62. The apparatus asclaimed in claim 61, wherein the gripping tool, which can be driven torotate and is at the same time used as a coil core for the lowerprotective strip is held in a spindle which itself is mounted such thatit can move axially in a hollow shaft which is mounted such that it canrotate and can be driven to rotate, and is coupled to a linear movementdrive, wherein the closing and opening movement of the gripping tool isderived from the axial movement of the spindle.
 63. The apparatus asclaimed in claim 52, wherein the gripping tool, which can be driven torotate and is at the same time used as a coil core for the lowerprotective strip, is in the form of a suction strip, which can movewithin the application tool and to which air or a vacuum can be appliedin a controlled manner, which suction strip has an approximatelysemicircular or D-shaped cross section, has a sucking contact surface onthe flat face, and whose contact surface can be applied to thestart-side projection of the film composite that is held in theapplication tool.
 64. The apparatus as claimed in claim 52, wherein thegripping tool, which can be driven to rotate and is at the same timeused as a coil core for the lower protective strip, can be moveddeliberately to a rotation position such that the picking-up surface ofthe gripping tool is ready to pick up parallel to the start-sideprojection of the film composite which is held in the application tool.65. The apparatus as claimed in claim 52, characterized in that therotation speed of the rotary drive of the gripping tool which is used atthe same time as a coil core can be controlled during the windingprocess such that an at least approximately constant circumferentialspeed of the coil which can be predetermined, can be maintainedirrespective of an increasing diameter of the coil.
 66. The apparatus asclaimed in claim 52, wherein the wiper and the gripping tool areconnected to one another, or are coupled to one another and can be movedat the same speed, with a fixed association (distance A) in the workingposition.
 67. The apparatus as claimed in claim 52, wherein theintensity of the vacuum during the time in which it can be applied canbe varied separately at least for the end suction gripper such that thefixing force can be varied towards the end of the wiping-on process inthe sense of allowing it to continue to slide.
 68. The apparatus asclaimed in claim 52, wherein the wiper can be pressed onto the filmblank and/or onto the bodywork part which is held inflexibly with alinear pressure amounting to 10 to 50 N/cm.
 69. The apparatus as claimedin claim 52, wherein the wiper is composed of a hard felt with athickness of about 10 to 20 mm.
 70. An elongated, prefabricated paintfilm composite which is intended for application to specific bodyworkparts, in which a usable paint film blank is provided both on theoutside and underneath with an adherent but easily detachable protectivestrip, wherein for automated application of the paint film blank bymeans of an application tool, which can be handled by means of aprogrammable industrial robot, to the film composite, both the outerprotective strip and the lower protective strip each project beyond thepaint film blank at the two ends which are located in the area of thenarrow faces of the paint film blank, wherein the length, measured inthe longitudinal direction of the film blank, of one projection, isapproximately matched to the attachment width (b2) of the associatedsuction gripper measured in the longitudinal direction of the paint filmblank while, in contrast, the length of the other projection, which islikewise matched approximately to the attachment width (b₁) of theassociated suction gripper wherein, however, at least the lowerprotective strip is lengthened beyond the said attachment width (b₁) onthe other side projection by a specific gripping length in order to begripped by a protective strip pulling-off apparatus.
 71. The paint filmcomposite as claimed in claim 70, wherein a supporting film whichcorresponds to the thickness of the paint film, is in each case insertedbetween the two protective strips in the area of the projections of theprotective strips, such that the film composite has three layers overthe entire length of at least the outer protective strip and has auniform thickness with the exception of a plurality of narrowinterruptions.
 72. The paint film composite as claimed in claim 71,wherein, in the area of the other projection the upper protective stripis also lengthened by the gripping length beyond said attachment width(b₁) and is connected to the lengthened lower protective strip with asupporting film inserted between them, and in that the upper protectivestrip and the supporting film are slotted at the same point and over theentire width of the film composite along a line which runs transverselywith respect to the longitudinal direction of the film composite andwhich is located in the area between the other projection and thepulling-off lug around said gripping length while, in contrast, thelower protective strip is also continuous at this point.
 73. The paintfilm composite as claimed in claim 70, wherein the supporting film isidentical to the paint film but is separated from the usable part of thepaint film blank by an interruption.
 74. The paint film composite asclaimed in claim 70, wherein the lower protective strip is provided withan antistick coating such that it is easier to detach the lowerprotective strip from the adhesive face of the paint film blank than todetach the latter from the outer protective strip.
 75. The methodaccording to claim 49, wherein the linear pressure is between 2D and 30N/cm.
 76. The method according to claim 51, wherein said one suctiongripper is the start-side suction gripper.
 77. The apparatus of claim57, wherein the stops are between 15 and 30 degrees.